Processing Mechanism And Experimental Study Of CFRP Based On Water Jet Guided Laser Processing

Carbon fiber-reinforced polymer composites(CFRP)is a new type of composite material with resin as matrix and carbon fiber as reinforcement.It has high specific strength,high specific modulus,high specific heat capacity,low density,low coefficient of thermal expansion and good thermal stability.It has been widely used in aerospace,military products and automotive industry,which can effectively reduce weight and cost.However,it has complex anisotropy,low interlaminar strength and easy to be destroyed,so it is a kind of difficult to machine material.At present,when cutting CFRP with traditional machining method,there are inevitable problems such as fiber fracture,delamination and burr;when cutting CFRP with traditional dry laser machining method,there are problems such as large heat affected zone and fiber end expansion,and it is difficult to cut large thickness CFRP due to laser divergence and shadow effect.Water jet guided laser processing technology is a combination of laser and water jet processing technology.It has the characteristics of no wear,no contact and flexible processing.It has potential advantages in reducing the heat affected zone(HAZ)and increasing the cutting depth.Firstly,the principle of water jet guided laser processing technology and material removal mechanism are described in this paper.The water jet state and the total reflection light guide of laminar flow interface are analyzed,and the laser attenuation and plasma phenomenon in water are studied.The selection requirements of pulse laser in pulse frequency,pulse width and so on for water jet guide laser processing are expounded.Secondly,according to the shape of the real water gas interface,the water gas layer water column structure is constructed,and the laminar light transmission characteristics in the water jet guided laser processing system are simulated and analyzed by ZEMAX software,and the changes of light distribution along the radial direction in different axial positions are studied.Thirdly,according to the mechanism and theoretical basis of water jet guided laser processing,and combined with the results of simulation analysis,the coupling device of laser and water jet is designed,and a set of water jet guided laser processing system is built.The coupling efficiency and power loss of the system are analyzed.The influence of water pressure on laminar flow length,the influence of auxiliary gas on laminar flow length and light transmission efficiency are studied,and the influence of water pressure on water jet guided laser processing system is analyzed.The results of cutting CFRP by laser and traditional dry laser are compared and analyzed,and the advantages of cutting CFRP by water jet guided laser and traditional dry laser are verified.Finally,the experimental study on the technology of water jet guided laser processing of CFRP was carried out.Single factor method and orthogonal experiment method were used to study the influence of key process parameters on the processing results of CFRP.Three damage mechanisms of CFRP cutting by water jet guided laser processing technology were summarized,which were fiber exposing,fiber pulling-out and fiber falling-off.In summary,the advantages of laser cutting CFRP are verified,which provides a reference for cutting thick carbon fiber reinforced composites.